Notable concerns about the quality and safety of our environment have evoked a growing awareness of the significant hazards associated with diverse organic and metal pollutants in groundwater associated with Superfund sites. Many of these prioritized target chemicals (TCs) can have severe and long lasting effects on health. The scope of the problem is broader still, since TCs routinely occur as complex chemical mixtures, the toxicities and interactions of which are ill-defined. Clearly, appropriate chemical intervention strategies for the remediation of polluted groundwater and the prevention of TC-induced disease in humans and animals are high priorities. In this project, our proposed aims are fourfold: i) to develop and/or characterize field-practical, clay-based adsorbents that can be used to bind and remove TCS from groundwater, ii) to chemically anchor these detoxifying clays onto inert matrices to enhance the water permeability and filtration capabilities of the clay- matrix composite, iii) to assess the effectiveness of prioritized clay composites for the removal of TCs from contaminated groundwater effluents at selected Superfund sites and to predict the successful decontamination and detoxification of this groundwater via chemical and biological analyses, and iv) to determine the efficacy of high capacity, high affinity detoxifying clays in the chemoprevention of TC-induced toxicity in vivo. In a newly reported procedure form our laboratory, hydrophilic and hydrophobic clay minerals have been chemically bonded to sand and utilized as a method for dramatically improving the discharge capacity of montmorillonate clays, while retaining their sorptive characteristics and improving their contact with the carrier medium. A distinct advantage of this model over existing methods of water treatment is the increased bulk density of the sand-immobilized clay product, which is now amenable to large scale processing of groundwater via in-line columns or existing fixed-bed sand filtration systems. Further research is clearly warranted to delineate optimal clays and clay-based sorbent systems for the remediation of polluted groundwater.